Fever: How high is too high and when should I worry?

The dreaded fever. Every parent’s question: how high is too high and when should I worry? Thanks to Blannie Cheng Miller from Raleigh, North Carolina for the great question.  “My 2 year old son recently started preschool. For the first 2 months, like clockwork, he (and then the rest of the family) gets a new 7-10 day virus, every 7-10 days. Every time he gets a virus, he develops a fever. We give him Motrin (and sometimes add Tylenol). Absent any ear-tugging or obvious source of infection, how high can his temp be before I call the doc? What about after he’s had Motrin?”

To start, let’s review some important information about fevers. Don’t be afraid! Fevers at the start of a childhood illness are generally your friend (I’ll explain this in a minute). A fever is an elevation in your child’s body temperature above 38C or 100.5F. This typically happens for two main reasons. 

• Infection

• Inflammation

First, let’s talk about fevers and infection. Children have an active, developing immune system. Much of childhood is spent building and fine-tuning the immune system. Development of the immune system happens by two main processes: getting sick and vaccination. I have a lot to say about vaccines, but we can talk about that in another post. Let’s focus on infection. 

Children get A LOT of viruses. Many childhood viral illness start with fever in the first day or two of the illness. As mentioned in Blannie’s question, the typical kid in a daycare or school setting gets sick pretty regularly. For most children, this means a new virus at least once a month. AT LEAST. It is not uncommon for children to get sick even more frequently than this, especially during the winter cold and flu season. Often it will seem like children are getting one illness after another and essentially have a runny nose for about 6 months out of the year for the first few years of their lives. UGH. This is rough on everyone. But remember, getting sick is a necessary evil for the development of a healthy and robust immune system. 

Most childhood illness are accompanied by a fever. Why? Great question. 

Your body is actually pretty smart. It turns out that fevers may be a defense mechanism for fighting off infection. Many viruses and bacteria prefer to live and grow at the same temperature as our normal body temperature. By raising your body’s temperature setting, it is thought that the nasty little bugs become less effective at growing. This gives your body the upper hand and helps your body’s immune system to fight off the infections even FASTER! Pretty brilliant, isn’t it? 

The downside is that fevers make kids feel rotten. They will often just want to lay around and do very little of anything. Parents get worried because this is typically very out of character for their lively, active child with endless energy. Remember, however, that your child is acting the same way you *want* to act when you are sick. Who wouldn’t want to lay around, do nothing, and have someone take care of them when sick? Not to mention, the more laying around kids do, the more likely they are to rest and allow their little bodies to spend all of their energy on fighting off the infection. It’s not fun, but it does make sense. 

So, am I suggesting that we just let our kids be miserable for days? Of course not. Deciding when to treat a fever can be a little tricky. My best advice is to treat the symptoms and not focus as much on the exact number. Whether your child has a fever or 101F or 103F isn’t nearly as important as how they are acting. If your child has a temperature of 103F but is happy and playing, don’t worry about it too much. Leave the fever alone to do its job to help fight off the infection. If, however, your child’s temperature is 103F and they are miserable - not drinking, not eating, not playing, nothing - treat them. Give them a dose of ibuprofen or acetaminophen and let the medicine do its work to perk your child back up again. 

Do pay special attention to whether or not your child is getting enough to drink. Eating well matters less during the few days of an acute illness. Drinking well matters A LOT. For little ones, especially breast fed babies, it may be difficult to know how much fluid they are drinking. Count the diapers instead. Babies should have a wet diaper at least every 6 hours. Toddlers need an average of 1-2 ounces of fluid per hour. One trick is to mix Pedialyte with a little apple juice and put a squirt or two in their mouth every few minutes using a medicine syringe. Time consuming, yes. But, also effective.  

There are a few exceptions to the general guidance for HEALTHY children as outlined above: 

1.     NONE of this applies to children under three months of age. If you child is three months or less and has a fever greater than 100.5F, CALL YOUR DOCTOR. NOW. 

2.     If you child has had a fever every day for the past 5 days of greater than 100.5F, CALL YOUR DOCTOR. 

3.     If your child’s fever is not responding to ibuprofen or acetaminophen, i.e., they are not perking up within about 30-60 min of giving the medicine. CALL YOUR DOCTOR. 

4.     Similarly, if you child is listless, not responding well to you, acting confused or with an altered mental status or any other concerning signs, CALL YOUR DOCTOR.

5.     If your child has a fever and NO OTHER SYMPTOMS, you should call your doctor after 2 days of fever. 

6.     If you child has a fever of 104F that does not come down with medicine, or a temperature of 105F, CALL. This level of fever is not necessarily an emergency, but it is important to talk it over with your doctor to make sure. 

7.     If you child has been sick for several days and the fever comes in the middle of the illness instead of at the beginning, it is worth calling your doctor. This may be the sign of a secondary infection that needs to be evaluated by your doctor. 

8.     If you are worried despite reading this information, CALL. Any pediatrician should welcome your calls and provide reassurance (or an appointment!!) when needed. 

9.     If your child is unvaccinated or under-vaccinated, call sooner. These children are at a higher risk for serious infections. 

10.   If you child has a special medical condition that makes fevers a different beast for your child - such as cancer, sickle cell disease, a chronic medical issue, or a compromised immune system for another reason - Please follow the guidelines for fever that your child’s doctor as outlined for your specific child.  

What about teething? 

The other time that kids will often get fever that is NOT necessarily related to infection is due to inflammation in the body. For little kids, this commonly happens with teething. Most kids will start teething around 4-6 months of age and generally continue intermittently for the next several months. A second round of teething sets in around age 2, when kids are getting a set of molars. Most of the time, a fever related to teething is usually in the 99-100F range. If your baby is uncomfortable and not sleeping well due to teething and the associated fever, it is usually fine to give your little one a dose of ibuprofen or acetaminophen. You don’t want to be doing this every day, but a few doses over the course of a month are typically fine. 

Should I alternate acetaminophen and ibuprofen?

Many people recommend alternating dosing of acetaminophen and ibuprofen such that a different medicine can be given every 3 hours. While this strategy may lead to quicker return to a normal temperature, there is not strong evidence to support the idea that alternating ibuprofen and acetaminophen is actually better overall. In fact, the AAP does not recommend combining the medications due to the possible risk of improper dosing and increased side effects. 

Can fevers cause seizures? 

And one more thing, as I am sure someone was thinking it - fevers themselves do not cause seizures. Yes, there is such a thing as a febrile seizure, but this is not the same thing as a fever causing a seizure. Febrile seizures are a type of seizure disorder which affects a small proportion of children. While scary to see, febrile seizures are mostly harmless. For children who are pre-disposed to this condition, seizures typically happen in the setting of fevers that rise quickly. For these kids, it is more important how quickly the fever rises rather than how high it gets. Unfortunately, for kids who are going to have febrile seizures, it will happen regardless of what you do. Even if you gave your child ibuprofen every single day, it would still happen. 

So, please don’t let the possibility of a seizure be a reason to worry excessively about fevers. 

Last tip: If you tell me that your child has had a fever at home, I (and also likely your pediatrician) will believe you. You do not need to withhold medication in order to allow them to still have a fever when you come into the office for your visit. 

In summary, you are your child’s best advocate. If you are worried about your child, always please call. This information cannot cover every possible situation related to fevers, but hopefully it can serve as a general guideline for what to do when your otherwise healthy child gets a fever — or two, or three! 

REFERENCES: 

1) Fever: beneficial and detrimental effects of antipyretics. Greisman LA, Mackowiak PA. Curr Opin Infect Dis. 2002;15(3):241. 

2) Perspective on fever: the basic science and conventional medicine. Cannon JG.Complement Ther Med. 2013 Apr;21 Suppl 1:S54-60. doi: 10.1016/j.ctim.2011.08.002. Epub 2011 Sep 17

3) Fever in infants and children: Pathophysiology and management. Ward, MA. www.uptodate.com. updated May 2019

3) Febrile Seizures. Kids Health. https://kidshealth.org/en/parents/febrile.html

4) Fever and antipyretic use in children.Section on Clinical Pharmacology and Therapeutics, Committee on Drugs, Sullivan JE, Farrar HC, Pediatrics. 2011;127(3):580. 

5) Combined and alternating paracetamol and ibuprofen therapy for febrile children. Wong T, Stang AS, Ganshorn H, Hartling L, Maconochie IK, Thomsen AM, Johnson DW. Cochrane Database Syst Rev. 2013.